It is well known that internal free cut edges along this side seam panel or flap of a thermoplastic coated paperboard container are a serious problem in that the exposed paper fibers can absorb product or impart off-flavors to some products. One solution is skive and hem the internal cut edge of the side seam panel.
Typically, the entire skiving operation is accomplished on each container individual blank while being processed through the side seam sealing machine. For example, U.S. Pat. No. 3,604,317 discloses a cut edge formed partially through the blank thickness by a cutting knife a predetermined distance from a blank outer edge while the individual blanks are being fed through the side seal sealing machine. A skived area surface is then formed by a skiving milling blade serving to remove the material between the cut edge and the outer edge. The remaining material is then formed in such a manner that the skived area surface is folded across the cut edge and onto the adjacent outside surface.
U.S. Pat. Nos. 3,604,613 and 3,654,842 disclose side seam sealed containers, wherein approximately one-half the thickness of each container blank has been removed adjacent the edge of the side seam panel thereof. In 3,604,613 a fold line has been formed on the blank's inside surface along the center line of the skived area surface, while in 3,654,842 a notch has been formed on the skived surface itself along the center line thereof.
Inasmuch as the side seam sealing machine is a very high speed machine, it is very difficult to maintain the necessary accuracy and parallelism of the skived width and adjacent crease line with respect to the free edge of the blank.